Preferred or optimum operating RPM

General help and support for your Lindeman through 2010 John Deere crawler
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bscrawler
40C crawler
40C crawler
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Location: Otsego county NY

Preferred or optimum operating RPM

Post by bscrawler » Sun Aug 29, 2021 1:55 pm

I know the operators manual says full open throttle then select gear for best operating , but what would be suggested by others. for good performance and less lugging of the engine during general operation pushing fill dirt, general grade work . Just wondering about this machine and rpm ranges for better engine temps while working and running 3-4 hours at a time . .
1/2 3/4 throttle? Rpm range to stay within ? .stay Over this much or below this much ? Rpm range to keep good charging power or proper pto speed .

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Lavoy
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Re: Preferred or optimum operating RPM

Post by Lavoy » Sun Aug 29, 2021 5:58 pm

No one good answer, it all depends on conditions. If digging hard dirt, or heavy load, full throttle. If backfilling next to a building or something like that, lowest throttle that provides necessary power. All depends on operator and preference.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
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bscrawler
40C crawler
40C crawler
Posts: 11
Joined: Fri Aug 13, 2021 5:13 am
Location: Otsego county NY

Re: Preferred or optimum operating RPM

Post by bscrawler » Tue Aug 31, 2021 5:53 am

I think I have found what I was looking for . @ 1400 rpm develop max torque and @1800 we are getting rated pto speed . 14-18 for working and anything below is Sunday driving . But every piece of equipment we have some sort of a sweet spot for running her . Thanks

Jim B
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Re: Preferred or optimum operating RPM

Post by Jim B » Tue Aug 31, 2021 6:51 am

Lavoy has the answer. As you operate it you will find you need to vary the rpms more than 1400 to 1800 rpms, especially to the lower side. That rpm range is ok out in the open just pushing dirt. With a hydrostatic drive you can keep rpms up and slow the drive to work around things. With your 420's mechanical drive, gear changes and varying engine speed is the method to deal with fine work, sometimes you have to slow the engine rpms even when in first gear for fine movements. You don't want to be keeping the rpms up and slipping the engine clutch to slow travel. Ideal rpm for torque or PTO isn't always ideal for the work conditions. As you get used to operating it you will find what works for you in the varying conditions.

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